The proposed implementation research addresses a longstanding and vexing problem in behavioral health care: Access to integrated services for persons with co-occurring substance use and mental health disorders. Despite decades of awareness of this problem, at present, less than 10% of treated patients with co-occurring disorders receive evidence-based integrated services. Implementation science holds to key to addressing this persistent gap. The present study unifies and operationalizes three major implementation research heuristics: the Consolidated Framework for Implementation Research, the Stages of Implementation Completion, and the Proctor et al (2011) taxonomy of implementation outcomes. Developed by industrial engineers, a multi-faceted implementation strategy, NIATx, has proven to be effective in implementing and sustaining simple interventions in behavioral health care services. The overarching goal of this project is to test whether NIATx strategies are effective in implementing a complex evidence-based intervention: Integrated services for persons with co-occurring disorders. Promising pilot data suggest that NIATx actually can integrate services, but a more rigorous study is needed. We now take this step and herein propose a cluster randomized wait-list control group design, in which a cohort of 23 agencies receive the active NIATx approach while the other cohort of 23 agencies are waitlisted. In the second phase, the wait-list group of 23 agencies participates in NIATx and the initial group enters a sustainment phase. Hypothesized to install and sustain integrated services, NIATx is examined for effectiveness on two core implementation outcomes: fidelity and penetration, as well as patient care outcomes (psychiatric and substance use symptom reduction). Variation in the extent of and fidelity to which NIATx strategies are delivered are evaluated using the NIATx Fidelity Scale, which embeds the Stages of Implementation Completion measure. Primary outcomes are assessed at pre- implementation, post-implementation and at sustainment follow-up periods. Qualitative and economic analyses augment the quantitative data, and add to the interpretation of organizational and social dynamics, as well as resource costs. We assemble a multi-disciplinary research team with considerable and complementary expertise and experience. Capitalizing on a technically sophisticated clinical management information capacity across a state system of care (Washington), the study engages representative outpatient programs across 20 counties. Consistent with US data, the participating agencies and their key stakeholders are highly motivated to improve services for patients with co-occurring disorders. Practical implementation strategies, including their associated costs, and the measurable impact on services and patient outcomes, will be definitive research products. Findings from this robust study are immediately applicable to improve clinical services, to advance implementation research, and ultimately, to guide future implementations with other behavioral health systems and settings.